Adhesive Panels of Microvane Arrays for Reducing Effects of Wingtip Vortices

ABSTRACT

In one embodiment, a wing includes a low pressure side, a high pressure side opposite the low pressure side, and a drag reducing apparatus coupled to the low pressure using an adhesive. The drag reducing apparatus includes a first side coupled to the low pressure side of the wing, and a second side opposite the first side, the second side comprising a plurality of vortex generators arranged in an array configuration, the array configuration of vortex generators operable to weaken a wingtip vortex generated by the wing by generating one or more vane vortices near an end of the low pressure side of the wing.

TECHNICAL FIELD

This disclosure generally relates to drag reduction systems for wingsand more specifically to adhesive panels of microvane arrays forreducing adverse effects of wingtip vortices.

BACKGROUND

Wingtip vortices are patterns of rotating air left behind a wing as itgenerates lift. Wingtip vortices may typically form at the end of thewing (e.g., the tip of an aircraft wing) but may also occur at otherpoints along the wing with abrupt structural changes (e.g., at the edgeof flap devices on a wing). Wingtip vortices may be associated withincreased drag forces, and thus may cause inefficiencies.

SUMMARY OF PARTICULAR EMBODIMENTS

According to one embodiment, a wing includes a low pressure side, a highpressure side opposite the low pressure side, and a drag reducingapparatus coupled to the low pressure using an adhesive. The dragreducing apparatus includes a first side coupled to the low pressureside of the wing, and a second side opposite the first side, the secondside comprising a plurality of vortex generators arranged in an arrayconfiguration, the array configuration of vortex generators operable toweaken a wingtip vortex generated by the wing by generating one or morevane vortices near an end of the low pressure side of the wing.

Technical advantages of certain embodiments may include providingreduced aerodynamic drag upon wings and/or reducing wake turbulencebehind wings by reducing wingtip vortices. Some embodiments may providedrag reduction systems at a lower weight and/or lower cost thantraditional drag reduction systems. Furthermore, some embodiments mayprovide drag reduction systems that require less aircraft downtime thantraditional drag reduction systems. Other technical advantages will bereadily apparent to one skilled in the art from the following figures,descriptions, and claims. Moreover, while specific advantages have beenenumerated above, various embodiments may include all, some, or none ofthe enumerated advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a typical aircraft wing without drag reductionapparatuses, according to certain embodiments.

FIG. 1B illustrates an example aircraft comprising a wing with nowinglet and a wing with a winglet, according to certain embodiments.

FIGS. 1C-1D illustrate an example wing with no winglet and with awinglet, respectively, according to certain embodiments.

FIG. 2 illustrates an example wing comprising adhesive panels ofmicrovane arrays, according to certain embodiments.

FIGS. 3A-3B illustrate an example adhesive panel comprising one or moremicrovane arrays, according to certain embodiments.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Typical wing designs may allow for the creation of large vortices at oraround the ends of the wing, such as at the tip of an aircraft wing.These vortices may increase wake turbulence behind the wing, which maycause issues for other wings following behind. For example, waketurbulence may cause a trailing aircraft to become difficult orimpossible to control. Furthermore, these vortices may add to the dragforces applied to a wing, and may therefore create fuel burninefficiencies for the aircraft using the wing. Reducing wing vorticesis therefore advantageous. Current techniques for reducing wing vorticesthrough the addition of drag reduction apparatuses, however, may requiresubstantial downtime for the aircraft and/or substantial expense. As anexample, one current technique for reducing wing vortices includesretrofitting aircraft with winglets. The addition of these winglets toan already-deployed aircraft may require millions of dollars and manyweeks of downtime.

Accordingly, teachings of the present disclosure provide a simple, lowcost, modification that may be applied to an already-deployed aircraftthat allows for reduction in the amount of drag applied to the wing andwake turbulence behind the wing. In particular embodiments, this may bedone by decreasing the strength of the wing vortices through the use ofone or more microvane arrays incorporated in an adhesive panel, whichmay easily be applied to already-deployed or already-created wings.Microvanes may refer to small-scale (relative to the wing chord length)vortex generators oriented approximately normal to airflow along asurface of a wing that redirect air as it flows over the wing. The sizeof the microvane array vortex generators may be on the order of theheight of the wing boundary layer, while winglets may often be sized toa height on the order of the wingtip chord length. The microvane arraysgenerate a series of co-rotating vortices that flow over the wing tipand serve to weaken the rotational strength of the wingtip vortex byaerodynamically or fluid dynamically thickening the apparent radius ofwingtip without requiring any physical changes to the wingtip radiusstructure. In particular embodiments, an adhesive panel comprising oneor more arrays of microvanes may be positioned on the low pressure sideof a wing such that air flowing over the low pressure side is displaced,weakening the strength of the resulting wingtip vortices. While themicrovane arrays may displace air flowing on the low pressure side of awing, it will be understood that the microvanes contemplated by thepresent disclosure may have a minimal effect on the overall aerodynamicproperties of the wing.

The adhesive panel of microvane arrays may be composed of any suitablematerial for use on the exterior of an aircraft, such as aluminum,titanium, polymer or reinforced polymer material, or composite material.In certain embodiments, the array of microvanes may be arranged ororiented in such a way that maximizes the drag reduction for theparticular aircraft design on which the array is installed. For example,the arrangement and/or orientation of microvanes for a BOEING 747 wingmay be different than those for a BOEING 777 wing. Such designs mayinclude provisions for whether or not the aircraft currently haswinglets installed. Furthermore, in some embodiments, the adhesive panelmay include one or more markings indicating proper alignment of theadhesive panel during installation on the wing. For example, lines ordots may be included on the adhesive panel that correspond to particularfeatures of a wing, allowing an installer to properly align the panelduring installation by aligning the markings with the correspondingfeatures of the wing. Examples of wing features that can be used toalign the adhesive panel include skin seams, rivet lines and otherobvious wing features. The adhesive panels may be coupled to anysuitable portion of the aircraft, including without limitation the lowpressure side of a wing on the aircraft (e.g., the top side of a wing).

To facilitate a better understanding of the present disclosure, thefollowing examples of certain embodiments are given. In no way shouldthe following examples be read to limit, or define, the scope of thedisclosure. Embodiments of the present disclosure and its advantages arebest understood by referring to FIGS. 1 through 3, where like numbersare used to indicate like and corresponding parts. Although embodimentsof the present disclosure are illustrated with respect to wings andaircraft, it will be understood that the teachings of the presentdisclosure may be applied to any suitable vehicle with panels thatcreate vortices, such as watercraft, in order to increase the vehicle'sefficiency.

FIG. 1A illustrates a typical aircraft wing 100 without drag reductionapparatuses, according to certain embodiments. When an airfoil such aswing 100 generates aerodynamic lift, the air on the top surface of theairfoil has lower pressure relative to the bottom surface of theairfoil. With reference to FIG. 1A, air flowing over wing 100 has alower pressure relative to the air flowing under wing 100. Because ofthis, air flows from below wing 100 and around the tip to the top ofwing 100 in a circular fashion, and an emergent circulatory flow pattern(i.e., a vortex) is formed. In addition, vorticity sheets 101 may beformed behind wing 100 as a result of the pressure differential. At theend of wing 100 (or any other abrupt structural change in the wing, suchas at a flap opening), vorticity sheets 101 may become vortices 110 asshown in FIG. 1A. Vortices 110 may cause increased drag upon wing 100(and thus the entire aircraft), creating fuel burn inefficiencies.

One method of reducing the drag forces induced by vortices 110 is theuse of winglets. FIG. 1B illustrates an example aircraft 150 comprisingwing 151 with no winglet and wing 152 with winglet 160, according tocertain embodiments. Winglets 160 may increase the effective aspectratio of wing 152 (as compared with the aspect ratio of wing 151), thuschanging the pattern and magnitude of the vorticity sheets and vorticesproduced by the wing as illustrated by FIGS. 1C-1D. The reducedmagnitude of the vorticity sheets and vortices means less effort isexpended by aircraft 150, reducing the amount of fuel used by aircraft150. While winglets 160 may serve to reduce wingtip vortices and drag,the addition of winglets 160 to aircraft (especially to currentlydeployed aircraft) may be quite expensive and may require substantialdowntime for the aircraft. For example, the addition of winglets 160 toa currently deployed aircraft may cost more than one million dollars peraircraft and may require many weeks of downtime to install.

Accordingly, a simpler, low cost solution to reducing wingtip vorticesmay be desired, such as adhesive panels of microvane arrays according tothe teachings of the present disclosure. Adhesive panels of microvanearrays may provide an alternative to current drag reduction systems suchas winglets 160. For example, rather than choosing to install winglets160 on an aircraft to reduce drag, an owner may choose instead toinstall the adhesive panels of microvane arrays. However, it will alsobe understood that adhesive panels of microvane arrays may be used inconjunction with current drag reduction systems such as winglets 160.

Modifications, additions, or omissions may be made to FIGS. 1A-1Dwithout departing from the scope of the present disclosure. For example,the design of aircraft wing 100, and thus the shape or size of vortices110, may differ slightly for different aircraft, but the principlesillustrated and discussed herein may not change. As another example, thesize and/or shape of aircraft 150 and the components thereof (e.g.,winglet 160) may differ for different aircraft, but the principlesillustrated and discussed herein may not change.

FIG. 2 illustrates an example wing 200 comprising adhesive panels ofmicrovane arrays 250, according to certain embodiments. Wing 200 may bea wing of an aircraft in particular embodiments, and may comprise awingtip 210 and one or more flaps 220. The adhesive panels of microvanearrays 250 may comprise a plurality of vortex generators configured inarrays in order to redirect low pressure air flowing over wing 200and/or inhibit high pressure air flowing upward from under wing 200. Theredirection of air flow on the low pressure surface of wing 200 orinhibition of air flow from the high pressure surface of wing 200 mayhave the effect of making wing 200 behave as if it were thicker, thusweakening or displacing the wingtip vortices created at particular areasalong the wing.

The adhesive panels of microvane arrays 250 may be located on anysuitable surface of wing 200, such as at the end of the low pressuresurface of wing 200 (e.g., the end tip of wing 200 or end of a flap onwing 200). In certain embodiments, when air flows over the adhesivepanels of microvane arrays 250 on the low pressure surface of wing 200,one or more vane vortices 260 may be formed on the low pressure surfaceof wing 200 such that the vane vortices impede the circulation of therelatively high pressure air flowing upward from the high pressuresurface side of wing 200. The vane vortices 260 produced by microvanearrays 250 may therefore constrain the formation of the wingtip vortices270. As shown in FIG. 2, microvane arrays 250 may be positioned adjacentto the ends of wing 200, such as at the tip of the wing or on a flap ofthe wing, where wingtip vortices 270 may form during flight. In certainembodiments, the precise placement of the adhesive panels of microvanearrays 250 on wing 200 may be based on the specific wing application,such as the model of aircraft (e.g., BOEING 747) on which the adhesivepanels of microvane arrays 250 is installed.

In particular embodiments, adhesive panels of microvane arrays 250 maybe positioned on wing 200 such that the centers of vane vortices 260 maybe different from the centers of wingtip vortices 270. This may providean opposition region in which the vane vortex 260 and the wingtip vortex270 oppose each other, which may cause a combined effective vortex coreto be distributed between the vane vortices 260 and the wingtip vortex270. This may provide a rapid far field vortex dissipation effect,lessening the size of wingtip vortex 270. It will be understood,however, that although vane vortices 260 rotate in the same direction asthe wingtip vortex 270, the induced velocities of vane vortices 260 andwingtip vortex 270 reinforce each other, reducing or eliminating liftdegradation or induced drag on wing 200.

In particular embodiments, the adhesive panels of microvane arrays 250may comprise one or more markings 255 as shown in FIG. 2. Markings 255may include any suitable type of markings (e.g., lines) that indicateproper placement of adhesive panels of microvane arrays 250 on wing 200.In particular embodiments, markings 255 may indicate alignment withrespect to one or more of the features of wing 200. For example, asshown in FIG. 2, markings 255 align with the skin seams 256 on flap 220,indicating that the markings should align with the seam when theadhesive panel 250 is placed on to wing 200.

Modifications, additions, or omissions may be made to FIG. 2 withoutdeparting from the scope of the present disclosure. For example, thedesign of wing 200, including but not limited to the design of flaps220, may differ depending on the aircraft on which microvane arrays 250are installed. As another example, the placement of microvane arrays 250or the markings thereon may differ depending on the aircraft on whichmicrovane arrays 250 are installed.

FIGS. 3A-3B illustrate an example adhesive panel 300 comprising one ormore microvane arrays 310, according to certain embodiments. Adhesivepanel 300 may be composed of any suitable materials for use on a wing(i.e., rigid and relatively lightweight), such as aluminum, titanium,polymer or reinforced polymer materials, or composite materials. On oneside, adhesive panel 300 comprises an adhesive suitable for use incoupling the adhesive panel 300 to a wing (i.e., an adhesive that canwithstand high velocities and many different weather conditions). Forexample, the adhesive may be an epoxy. On the opposite side, adhesivepanel 300 comprises one or more microvane arrays 310. Microvane arrays310 may each comprise a plurality of vortex generators 320 configured ina particular arrangement, which may be determined by the design of thewing on which the microvane arrays 310 are to be installed. Themicrovane arrays 310 of adhesive panel 300 may be arranged withparticular vertical spacing 311 and horizontal spacing 312, which may bedetermined by the intended application (e.g., which aircraft theadhesive panel 300 is intended to be installed on). In certainembodiments, the vertical spacing 311 or horizontal spacing 312 may bebetween 0.1 and 1 inch.

The vortex generators 320 of microvane arrays 310 may be of any suitablesize and/or shape, and may be oriented in any suitable way. In certainembodiments, the design (including size, shape, or orientation(including the position relative to the wing or angle relative to thelow pressure surface)) of the vortex generators 320 of microvane arrays310 may be optimized for particular speeds of airflow. For example, thedesign of the vortex generators 320 may be optimized for cruising speedsof an aircraft (e.g., the average speed at which the aircraft fliesbetween takeoff and landing) on which the microvane arrays 310 are to beinstalled in order to maximize drag reduction over time. As anotherexample, the design of the vortex generators 320 on microvane arrays 310may be optimized for speeds (e.g., landing approach speeds) at whichhigh angles of attack and lift enhancing aircraft configurations such asflap extension tend to create or greatly enhance the strength of tipvortices in order to reduce wake turbulence.

In certain embodiments, the height of the vortex generators 320 ormicrovane array 310 may be within 0.25 and 0.5 inches. In certainembodiments, the shape of the vortex generators 320 of microvane arrays310 may be semi-spherical. In some embodiments, the shape of the vortexgenerators 320 of microvane arrays 310 may be rectangular. In otherembodiments, the shape of the vortex generators 320 of microvane arrays310 may be cone-shaped. In some embodiments, the shape of the vortexgenerators 320 of microvane arrays 310 may be pyramid-shaped (e.g.,triangular, square, pentagonal, or hexagonal).

In particular embodiments, the vortex generators 320 of microvane arrays310 may be oriented at an angle of approximately normal to a portion ofthe low pressure surface on which they are to be installed. However, inother embodiments, the vortex generators 320 of microvane arrays 310 maybe oriented at certain angles relative to the normal axis of the lowpressure surface on which they are to be installed, such as at 30 or 45degrees relative to the axis normal to the low pressure surface.

Modifications, additions, or omissions may be made to FIGS. 3A-3Bwithout departing from the scope of the present disclosure. For example,although illustrated as comprising three vortex generators 320 each,microvane arrays 310 may comprise any suitable number of vortexgenerators 320 and that each microvane array 310 of panel 300 maycomprise different numbers of vortex generators 320. As another example,although illustrated as comprising vortex generators 320 with the samesize shape, microvane arrays 310 may comprise vortex generators 320 withvarious sizes and/or shapes. As yet another example, althoughillustrated in an arrangement with uniform spacing, microvane arrays 310of adhesive panel 300 may be arranged in a non-uniform manner.

Herein, “or” is inclusive and not exclusive, unless expressly indicatedotherwise or indicated otherwise by context. Therefore, herein, “A or B”means “A, B, or both,” unless expressly indicated otherwise or indicatedotherwise by context. Moreover, “and” is both joint and several, unlessexpressly indicated otherwise or indicated otherwise by context.Therefore, herein, “A and B” means “A and B, jointly or severally,”unless expressly indicated otherwise or indicated otherwise by context.

The scope of this disclosure encompasses all changes, substitutions,variations, alterations, and modifications to the example embodimentsdescribed or illustrated herein that a person having ordinary skill inthe art would comprehend. The scope of this disclosure is not limited tothe example embodiments described or illustrated herein. Moreover,although this disclosure describes and illustrates respectiveembodiments herein as including particular components, elements,functions, operations, or steps, any of these embodiments may includeany combination or permutation of any of the components, elements,functions, operations, or steps described or illustrated anywhere hereinthat a person having ordinary skill in the art would comprehend.Furthermore, reference in the appended claims to an apparatus or systemor a component of an apparatus or system being adapted to, arranged to,capable of, configured to, enabled to, operable to, or operative toperform a particular function encompasses that apparatus, system,component, whether or not it or that particular function is activated,turned on, or unlocked, as long as that apparatus, system, or componentis so adapted, arranged, capable, configured, enabled, operable, oroperative.

What is claimed is:
 1. A wing, comprising: a low pressure side and ahigh pressure side opposite the low pressure side, wherein the lowpressure side and high pressure side are configured, when air flows overthe wing, to generate a force on the high pressure side; and a dragreducing apparatus coupled to the low pressure side of the wing using anadhesive, the drag reducing apparatus comprising: a first side coupledto the low pressure side of the wing; a second side opposite the firstside, the second side comprising a plurality of vortex generatorsarranged in a plurality of arrays, the plurality of arrays operable toweaken a wingtip vortex generated by the wing by generating one or morevane vortices near an end of the low pressure side of the wing; and oneor more markings, each of the one or more markings indicating alignmentof the drag reducing apparatus with respect to a feature of the wing. 2.The wing of claim 1, wherein the plurality of arrays are arranged suchthat centers of the generated vane vortices are different from centersof the wingtip vortex.
 3. A wing, comprising: a low pressure side and ahigh pressure side opposite the low pressure side, wherein the lowpressure side and high pressure side are configured, when air flows overthe wing, to generate a force on the high pressure side; and a dragreducing apparatus coupled to the low pressure side of the wing using anadhesive, the drag reducing apparatus comprising: a first side coupledto the low pressure side of the wing; and a second side opposite thefirst side, the second side comprising a plurality of vortex generatorsarranged in an array configuration, the array configuration of vortexgenerators operable to weaken a wingtip vortex generated by the wing bygenerating one or more vane vortices near an end of the low pressureside of the wing.
 4. The wing of claim 3, wherein the arrayconfiguration comprises a plurality of arrays, each array comprising aplurality of vortex generators.
 5. The wing of claim 4, wherein aspacing of the arrays of the plurality of arrays is between 0.1 and 1inch.
 6. The wing of claim 3, wherein the drag reducing apparatusfurther comprises one or more markings, each of the one or more markingsindicating alignment of the drag reducing apparatus with respect to afeature of the wing.
 7. The wing of claim 6, wherein a marking of theone or more markings indicates alignment with respect to a tip of thewing.
 8. The wing of claim 6, wherein a marking of the one or moremarkings indicates alignment with respect to a feature of a flap of thewing.
 9. The wing of claim 3, wherein each of the plurality of vortexgenerators is between 0.25 and 0.5 inches in height.
 10. The wing ofclaim 3, wherein a shape of the vortex generators is selected from thegroup consisting of semi-spherical, pyramid-shaped, and cone-shaped. 11.The wing of claim 3, wherein the array configuration is arranged suchthat centers of the generated vane vortices are different from centersof the wingtip vortex.
 12. A drag reducing apparatus comprising: a firstside comprising an adhesive, wherein the first side is configured to becoupled to a low pressure surface of a wing using the adhesive; and asecond side opposite the first side, the second side comprising aplurality of vortex generators arranged in an array configuration, thearray configuration of vortex generators operable to weaken a wingtipvortex generated by the wing by generating one or more vane vorticesnear an end of the low pressure surface of the wing.
 13. The apparatusof claim 12, wherein the array configuration comprises a plurality ofarrays, each array comprising a plurality of vortex generators.
 14. Theapparatus of claim 13, wherein a spacing of the arrays of the pluralityof arrays is between 0.1 and 1 inch.
 15. The apparatus of claim 12,further comprising one or more markings, each of the one or moremarkings indicating alignment of the apparatus with respect to a featureof the wing.
 16. The apparatus of claim 15, wherein a marking of the oneor more markings indicates alignment with respect to a tip of anaircraft wing.
 17. The apparatus of claim 15, wherein a marking of theone or more markings indicates alignment with respect to a feature of aflap of an aircraft wing.
 18. The apparatus of claim 12, wherein each ofthe plurality of vortex generators is between 0.25 and 0.5 inches inheight.
 19. The apparatus of claim 12, wherein a shape of the vortexgenerators is selected from the group consisting of semi-spherical,pyramid-shaped, and cone-shaped.
 20. The apparatus of claim 12, whereinthe array configuration is arranged such that centers of the generatedvane vortices are different from centers of the wingtip vortex.